What does a Lexus RX 400H intermittent Check Engine Light mean?

Hello, I disagree with the dealership. A check engine light will most likely set a diagnostic trouble code that can be traced - even from a "memory" historical occurrence, and give some data as to where to start looking. Since it happens frequently enough, a repair shop should even be able to drive the vehicle and duplicate the concern while testing anyway. There are quite a number of things that can cause the check engine light to come on, from emissions controls, to hybrid operation, to transmission operation to engine performance issues. Use this link to find some shops near you that can help with your concern: www.repairpal.com/repair-shops